This invention relates to Liquid Metal Ion (LMI) sources, and particularly to a method and apparatus for modulating an LMI source.
Focussed Ion Beam (FIB) micromachining or milling is presently conducted in an open loop manner. This means that the desired structure is laid out using conventional methods, a beam control program is written off-line and entered into a control computer which generates the FIB raster pattern for the milling process. In order to determine if the process has been properly carried out, the FIB may be used like a scanning electron microscope (SEM) for inspection of the workpiece, or, the milled workpiece may be removed from the milling station and placed in a SEM for post milling examination. In the event that further micro-machining is required, the workpiece must then be replaced in the milling station with proper registration and the process repeated or continued.
A raster pattern controls the FIB to hold the FIB over those areas which are intended for more intense milling for a longer period of time, while passing the FIB over those areas which require less milling in a shorter time span. Following each micro-machining process, the workpiece may be inspected again, such as by a scanning electron microscope. A FIB may be generated using an LMI source. Modulation of the LMI source will result in modulation of the FIB to further control the rate/depth of the micromachining or milling process.
An object of the invention is to provide an apparatus and method for modulating a liquid metal ion source.
Another object of the invention is to provide an apparatus and method for modulating an ion beam which is generated by a liquid metal ion source using a light beam source.
A further object of the invention is to provide a method and apparatus for controlling a FIB system to modulate the ion column to control a milling process.
Yet another object of the invention is to provide an apparatus and method for modulating a FIB to allow control of the depth of the milling of the work piece independently of the raster scanning rate.